Displaying publications 1 - 20 of 25 in total

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  1. Fulltext Understanding the Role of ztor in Aging-related Diseases Using the Zebrafish Model
    Khor ES, Noor SM, Wong PF
    In Vivo, 2019 10 31;33(6):1713-1720.
    PMID: 31662495 DOI: 10.21873/invivo.11661
    The mammalian target of rapamycin (mTOR), a 289 kDa serine/threonine protein kinase of the phosphoinositide 3-kinase (PI3K)-related family is known for its role in regulating lifespan and the aging process in humans and rodents. Aging in zebrafish very much resembles aging in humans. Aged zebrafish often manifest with spinal curvature, cataracts and cognitive frailty, akin to human age-related phenotypical effects such as osteoarthritis, dwindling vision and cognitive dysfunction. However, the role of the zebrafish orthologue of mTOR, ztor, is less defined in these areas. This review paper discusses the tale of growing old in the zebrafish, the physiological roles of ztor in normal developmental processes and its involvement in the pathogenesis of aging-related diseases such as metabolic disorders and cancers.
    Matched MeSH terms: Zebrafish/metabolism*
  2. The effects of metallothionein in paraquat-induced Parkinson disease model of zebrafish
    Mohamad Najib NH, Yahaya MF, Das S, Teoh SL
    Int J Neurosci, 2023 Dec;133(8):822-833.
    PMID: 34623211 DOI: 10.1080/00207454.2021.1990916
    INTRODUCTION: Parkinson's disease (PD) is the second most common neurodegenerative disease caused by selective degeneration of dopaminergic neurons in the substantia nigra. Metallothionein has been shown to act as a neuroprotectant in various brain injury. Thus, this study aims to identify the effects of full-length human metallothionein 2 peptide (hMT2) in paraquat-induced brain injury in the zebrafish.

    METHODOLOGY: A total of 80 adult zebrafish were divided into 4 groups namely control, paraquat-treated, pre-hMT2-treated, and post-hMT2-treated groups. Fish were treated with paraquat intraperitoneally every 3 days for 15 days. hMT2 were injected intracranially on day 0 (pre-treated group) and day 16 (post-treated group). Fish were sacrificed on day 22 and the brains were collected for qPCR, ELISA and immunohistochemistry analysis.

    RESULTS: qPCR analysis showed that paraquat treatment down-regulated the expression of genes related to dopamine activity and biosynthesis (dat and th1) and neuroprotective agent (bdnf). Paraquat treatment also up-regulated the expression of the mt2, smtb and proinflammatory genes (il-1α, il-1β, tnf-α and cox-2). hMT2 treatment was able to reverse the effects of paraquat. Lipid peroxidation decreased in the paraquat and pre-hMT2-treated groups. However, lipid peroxidation increased in the post-hMT2-treated group. Paraquat treatment also led to a reduction of dopaminergic neurons while their numbers showed an increase following hMT2 treatment.

    CONCLUSION: Paraquat has been identified as one of the pesticides that can cause the death of dopaminergic neurons and affect dopamine biosynthesis. Treatment with exogenous hMT2 could reverse the effects of paraquat in the zebrafish brain.

    Matched MeSH terms: Zebrafish/metabolism
  3. Naturally Occurring HMGB1 Inhibitor, Glycyrrhizin, Modulates Chronic Seizures-Induced Memory Dysfunction in Zebrafish Model
    Paudel YN, Khan SU, Othman I, Shaikh MF
    ACS Chem Neurosci, 2021 09 15;12(18):3288-3302.
    PMID: 34463468 DOI: 10.1021/acschemneuro.0c00825
    Glycyrrhizin (GL) is a well-known pharmacological inhibitor of high mobility group box 1 (HMGB1) and is abundantly present in the licorice root (Glycyrrhiza radix). HMGB1 protein, a key mediator of neuroinflammation, has been implicated in several neurological disorders, including epilepsy. Epilepsy is a devastating neurological disorder with no effective disease-modifying treatment strategies yet, suggesting a pressing need for exploring novel therapeutic options. In the current investigation, using a second hit pentylenetetrazol (PTZ) induced chronic seizure model in adult zebrafish, regulated mRNA expression of HMGB1 was inhibited by pretreatment with GL (25, 50, and 100 mg/kg, ip). A molecular docking study suggests that GL establishes different binding interactions with the various amino acid chains of HMGB1 and Toll-like receptor-4 (TLR4). Our finding suggests that GL pretreatment reduces/suppresses second hit PTZ induced seizure, as shown by the reduction in the seizure score. GL also regulates the second hit PTZ induced behavioral impairment and rescued second hit PTZ related memory impairment as demonstrated by an increase in the inflection ratio (IR) at the 3 h and 24 h T-maze trial. GL inhibited seizure-induced neuronal activity as demonstrated by reduced C-fos mRNA expression. GL also modulated mRNA expression of BDNF, CREB-1, and NPY. The possible mechanism underlying the anticonvulsive effect of GL could be attributed to its anti-inflammatory activity, as demonstrated by the downregulated mRNA expression level of HMGB1, TLR4, NF-kB, and TNF-α. Overall, our finding suggests that GL exerts an anticonvulsive effect and ameliorates seizure-related memory disruption plausibly through regulating of the HMGB1-TLR4-NF-kB axis.
    Matched MeSH terms: Zebrafish/metabolism
  4. Cholesterol lowering by Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 in adult zebrafish is associated with improved memory and involves an interplay between npc1l1 and abca1
    Lim FT, Lim SM, Ramasamy K
    Food Funct, 2017 Aug 01;8(8):2817-2828.
    PMID: 28725889 DOI: 10.1039/c7fo00764g
    This study assessed the cholesterol lowering effect of Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 using adult zebrafish. Animals were fed with a high cholesterol diet (HCD) with/without LAB for seven weeks. Serum and liver cholesterol was quantified using colorimetric and dye staining methods. Expressions of npc1l1 and abca1 in the liver and intestine and appa in the brain were quantified using RT-PCR. Serum and liver cholesterol was significantly lowered in LAB4- and LAB12-fed zebrafish (≤64% and ≤71%, respectively), with reduced liver cholesterol deposition. The cholesterol lowering effect was accompanied by down-regulation of npc1l1 in intestines (≤28.7%), up-regulation of abca1 in the liver (≥30.5%) and down-regulation of appa in the brain (≤24.5%). A moderately strong positive Pearson correlation (r = 0.617, p < 0.01) was found between appa and serum cholesterol. LAB-fed zebrafish exhibited improved spatial learning and memory. LAB4 and LAB12 can be potentially used in preventing hypercholesterolaemia and Alzheimer's diseases.
    Matched MeSH terms: Zebrafish/metabolism*
  5. Newly regenerated dopaminergic neurons in 6-OHDA-lesioned adult zebrafish brain proliferate in the Olfactory bulb and telencephalon, but migrate to, differentiate and mature in the diencephalon
    Vijayanathan Y, Hamzah NM, Lim SM, Lim FT, Tan MP, Majeed ABA, et al.
    Brain Res Bull, 2022 Nov;190:218-233.
    PMID: 36228872 DOI: 10.1016/j.brainresbull.2022.10.001
    In order to understand the biological processes underlying dopaminergic neurons (DpN) regeneration in a 6-hydroxydopamine(6-OHDA)-induced adult zebrafish-based Parkinson's disease model, this study investigated the specific phases of neuroregeneration in a time-based manner. Bromodeoxyuridine (BrdU) was administered 24 h before the harvest of brain tissues at day three, five, seven, nine, 12 and 14 postlesion. Potential migration of proliferative cells was tracked over 14 days postlesion through double-pulse tracking [BrdU and 5-ethynyl-2'-deoxyuridine (EdU)] of cells and immunohistostaining of astrocytes [glial fibrillary acidic protein (GFAP)]. Gene expression of foxa2 and nurr1 (nr4a2a) at day three, nine, 14, 18, 22 and 30 postlesion was quantified using qPCR. Protein expression of foxa2 at day three, seven, 14 and 22 postlesion was validated using the western blot technique. Double labelling [EdU and tyrosine hydroxylase (TH)] of proliferative cells was performed to ascertain their fate after the neuroregeneration processes. It was found that whilst cell proliferation remained unchanged in the area of substantial DpN loss, the ventral diencephalon (vDn), there was a transient increase of cell proliferation in the olfactory bulb (OB) and telencephalon (Tel) seven days postlesion. BrdU-immunoreactive (ir)/ EdU-ir cells and activated astrocytes were later found to be significantly increased in the vDn and its nearby area (Tel) 14 days postlesion. There was a significant but transient downregulation of foxa2 at day three and nine postlesion, and nr4a2a at day three, nine and 14 postlesion. The expression of both genes remained unchanged in the OB and Tel. There was a transient downregulation of foxa2 protein expression at day three and seven postlesion. The significant increase of EdU-ir/ TH-ir cells in the vDn 30 days postlesion indicates maturation of proliferative cells (formed between day five-seven postlesion) into DpN. The present findings warrant future investigation of critical factors that govern the distinctive phases of DpN regeneration.
    Matched MeSH terms: Zebrafish/metabolism
  6. Cloning and expression of tachykinins and their association with kisspeptins in the brains of zebrafish
    Ogawa S, Ramadasan PN, Goschorska M, Anantharajah A, Ng KW, Parhar IS
    J. Comp. Neurol., 2012 Sep 1;520(13):2991-3012.
    PMID: 22430310 DOI: 10.1002/cne.23103
    The tachykinins are a family of neuropeptides, including substance P (SP), neurokinin A (NKA), and neurokinin B (NKB), that are encoded by the tac1 (SP and NKA) or tac2/3 (NKB) genes. Tachykinins are widely distributed in the central nervous system and have roles as neurotransmitters and/or neuromodulators. Recent studies in mammals have demonstrated the coexpression of NKB and kisspeptin and their comodulatory roles over the control of reproduction. We have recently identified two kisspeptin-encoding genes, kiss1 and kiss2, in teleosts. However, such relationship between tachykinins and kisspeptins has not been demonstrated in non-mammalian species. To determine the involvement of tachykinins in the reproduction in teleosts, we identified tac1 and two tac2 (tac2a and tac2b) sequences in the zebrafish genome using in silico data mining. Zebrafish tac1 encodes SP and NKA, whereas the tac2 sequences encode NKB and an additional peptide homologous to NKB (NKB-related peptide). Digoxigenin in situ hybridization in the brain of zebrafish showed tac1 mRNA-containing cells in the olfactory bulb, telencephalon, preoptic region, hypothalamus, mesencephalon, and rhombencephalon. The zebrafish tac2a mRNA-containing cells were observed in the preoptic region, habenula, and hypothalamus, whereas the tac2b mRNA-containing cells were predominantly observed in the dorsal telencephalic area. Furthermore, we examined the coexpression of tachykinins and two kisspeptin genes in the brain of zebrafish. Dual fluorescent in situ hybridization showed no coexpression of tachykinins mRNA with kisspeptins mRNA in hypothalamic nuclei or the habenula. These results suggest the presence of independent pathways for kisspeptins and NKB neurons in the brain of zebrafish.
    Matched MeSH terms: Zebrafish/metabolism*
  7. Cloning and expression of kiss2 in the zebrafish and medaka
    Kitahashi T, Ogawa S, Parhar IS
    Endocrinology, 2009 Feb;150(2):821-31.
    PMID: 18927220 DOI: 10.1210/en.2008-0940
    Newly discovered kisspeptin (metastin), encoded by the Kiss1/KISS1 gene, is considered as a major gatekeeper of puberty through the regulation of GnRH. In the present study, we cloned a novel kisspeptin gene (kiss2) in the zebrafish Danio rerio and the medaka Oryzias latipes, which encodes a sequence of 125 and 115 amino acids, respectively, and its core sequence (FNLNPFGLRF, F-F form) is different from the previously characterized kiss1 (YNLNSFGLRY, Y-Y form). Our in silico data mining shows kiss1 and kiss2 are highly conserved across nonmammalian vertebrate species, and we have identified two putative kisspeptins in the platypus and three forms in Xenopus. In the brain of zebrafish and medaka, in situ hybridization and laser capture microdissection coupled with real-time PCR showed kiss1 mRNA expression in the ventromedial habenula and the periventricular hypothalamic nucleus. The kiss2 mRNA expression was observed in the posterior tuberal nucleus and the periventricular hypothalamic nucleus. Quantitative real-time PCR analysis during zebrafish development showed a significant increase in zebrafish kiss1, kiss2 (P < 0.002), gnrh2, and gnrh3 (P < 0.001) mRNA levels at the start of the pubertal phase and remained high in adulthood. In sexually mature female zebrafish, Kiss2 but not Kiss1 administration significantly increased FSH-beta (2.7-fold, P < 0.05) and LH-beta (8-fold, P < 0.01) mRNA levels in the pituitary. These results suggest that the habenular Kiss1 and the hypothalamic Kiss2 are potential regulators of reproduction including puberty and that Kiss2 is the predominant regulator of gonadotropin synthesis in fish.
    Matched MeSH terms: Zebrafish/metabolism
  8. Distribution of Kiss2 receptor in the brain and its localization in neuroendocrine cells in the zebrafish
    Ogawa S, Sivalingam M, Anthonysamy R, Parhar IS
    Cell Tissue Res, 2020 Feb;379(2):349-372.
    PMID: 31471710 DOI: 10.1007/s00441-019-03089-5
    Kisspeptin is a hypothalamic neuropeptide, which acts directly on gonadotropin-releasing hormone (GnRH)-secreting neurons via its cognate receptor (GPR54 or Kiss-R) to stimulate GnRH secretion in mammals. In non-mammalian vertebrates, there are multiple kisspeptins (Kiss1 and Kiss2) and Kiss-R types. Recent gene knockout studies have demonstrated that fish kisspeptin systems are not essential in the regulation of reproduction. Studying the detailed distribution of kisspeptin receptor in the brain and pituitary is important for understanding the multiple action sites and potential functions of the kisspeptin system. In the present study, we generated a specific antibody against zebrafish Kiss2-R (=Kiss1Ra/GPR54-1/Kiss-R2/KissR3) and examined its distribution in the brain and pituitary. Kiss2-R-immunoreactive cell bodies are widely distributed in the brain including in the dorsal telencephalon, preoptic area, hypothalamus, optic tectum, and in the hindbrain regions. Double-labeling showed that not all but a subset of preoptic GnRH3 neurons expresses Kiss2-R, while Kiss2-R is expressed in most of the olfactory GnRH3 neurons. In the posterior preoptic region, Kiss2-R immunoreactivity was seen in vasotocin cells. In the pituitary, Kiss2-R immunoreactivity was seen in corticotropes, but not in gonadotropes. The results in this study suggest that Kiss2 and Kiss2-R signaling directly serve non-reproductive functions and indirectly subserve reproductive functions in teleosts.
    Matched MeSH terms: Zebrafish/metabolism*
  9. High Melatonin Conditions by Constant Darkness and High Temperature Differently Affect Melatonin Receptor mt1 and TREK Channel trek2a in the Brain of Zebrafish
    Loganathan K, Moriya S, Parhar IS
    Zebrafish, 2018 10;15(5):473-483.
    PMID: 30102584 DOI: 10.1089/zeb.2018.1594
    Ambient light and temperature affect reproductive function by regulating kisspeptin and gonadotrophin-releasing hormone (GnRH) in vertebrates. Melatonin and melatonin receptors, as well as the two-pore domain K+ channel-related K+ (TREK) channels, are affected by light and/or temperature; therefore, these molecules could modulate kisspeptin and GnRH against ambient light and temperature. In this study, we investigated the effect of light and temperature, which affect melatonin levels in gene expression levels of TREK channels, kisspeptin, and GnRH. We first investigated the effects of different light and temperature conditions on brain melatonin concentrations by ELISA. Fish were exposed to either constant darkness, constant light, high temperature (35°C), or low temperature (20°C) for 72 h. Brain melatonin levels were significantly high under constant darkness and high temperature. We further investigated the effects of high brain melatonin levels by constant darkness and high temperature on gene expression levels of melatonin receptors (mt1, mt2, and mel1c), TREK channels (trek1b, trek2a, and trek2b), gnrh3, and kiss2 in the adult zebrafish brain by real-time polymerase chain reaction. Fish were exposed to constant darkness or elevated temperatures (35°C) for 72 h. trek2a, kiss2, and gnrh3 levels were increased under constant darkness. High temperature decreased gene expression levels of mt1, mt2, mel1c, and gnrh3 in the preoptic area, whereas other genes remained unchanged. Melatonin receptors, TREK channels, gnrh3, and kiss2 responded differently under high melatonin conditions. The melatonin receptors and the TREK channels could play roles in the regulation of reproduction by environmental cues, especially ambient light and temperature.
    Matched MeSH terms: Zebrafish/metabolism*
  10. Diurnal Rhythm of trek2a Expression is Associated with Diurnal Rhythm of gnrh3 Expression in Zebrafish
    Loganathan K, Moriya S, Parhar IS
    Zoolog Sci, 2019 04 01;36(2):167-171.
    PMID: 31120653 DOI: 10.2108/zs180111
    The two-pore domain potassium ion (K + ) channel-related K + (TREK) channel and melatonin receptors play roles in the regulation of reproduction in zebrafish. Since reproduction is regulated by diurnal rhythms, the TREK family and melatonin receptors may exhibit diurnal rhythms in expression. In this study, we aimed to investigate diurnal variations of the gene expressions of TREK family and melatonin receptors and their associations with kisspeptin and gonadotrophin-releasing hormone (GnRH). Diurnal variations of trek1b, trek2a, trek2b, mt1, mt2, mel1a, kiss2 and gnrh3 expressions were examined by real-time PCR. For reproduction-related genes, kiss2 and gnrh3 exhibited diurnal rhythms. trek2a revealed a diurnal rhythm in the TREK family. mt2 and mel1c exhibited diurnal rhythms in the melatonin receptors. Since Trek2a regulates gnrh3 expression, the diurnal rhythm of gnrh3 expression suggests to be regulated by the diurnal rhythm of trek2a expression.
    Matched MeSH terms: Zebrafish/metabolism*
  11. Temperature differentially regulates the two kisspeptin systems in the brain of zebrafish
    Shahjahan M, Kitahashi T, Ogawa S, Parhar IS
    Gen Comp Endocrinol, 2013 Nov 1;193:79-85.
    PMID: 23899715 DOI: 10.1016/j.ygcen.2013.07.015
    Kisspeptins encoded by the kiss1 and kiss2 genes play an important role in reproduction through the stimulation of gonadotropin-releasing hormone (GnRH) secretion by activating their receptors (KissR1 EU047918 and KissR2 EU047917). To understand the mechanism through which temperature affects reproduction, we examined kiss1 and kiss2 and their respective receptor (kissr1 and kissr2) gene expression in the brain of male zebrafish exposed to a low temperature (15°C), normal temperature (27°C), and high temperature (35°C) for 7-days. kiss1 mRNA levels in the brain were significantly increased (2.9-fold) in the low temperature compared to the control (27°C), while no noticeable change was observed in the high temperature conditions. Similarly, kissr1 mRNA levels were significantly increased (1.5-2.2-folds) in the low temperature conditions in the habenula, the nucleus of the medial longitudinal fascicle, oculomotor nucleus, and the interpeduncular nucleus. kiss2 mRNA levels were significantly decreased (0.5-fold) in the low and high temperature conditions, concomitant with kissr2 mRNA levels (0.5-fold) in the caudal zone of the periventricular hypothalamus and the posterior tuberal nucleus. gnrh3 but not gnrh2 mRNA levels were also decreased (0.5-fold) in the low and high temperature conditions. These findings suggest that while the kiss1/kissr1 system is sensitive to low temperature, the kiss2/kissr2 system is sensitive to both extremes of temperature, which leads to failure in reproduction.
    Matched MeSH terms: Zebrafish/metabolism*
  12. Early-life stress changes expression of GnRH and kisspeptin genes and DNA methylation of GnRH3 promoter in the adult zebrafish brain
    Khor YM, Soga T, Parhar IS
    Gen Comp Endocrinol, 2016 Feb 1;227:84-93.
    PMID: 26686318 DOI: 10.1016/j.ygcen.2015.12.004
    Early-life stress can cause long-term effects in the adulthood such as alterations in behaviour, brain functions and reproduction. DNA methylation is a mechanism of epigenetic change caused by early-life stress. Dexamethasone (DEX) was administered to zebrafish larvae to study its effect on reproductive dysfunction. The level of GnRH2, GnRH3, Kiss1 and Kiss2 mRNAs were measured between different doses of DEX treatment groups in adult zebrafish. Kiss1 and GnRH2 expression were increased in the 200mg/L DEX treated while Kiss2 and GnRH3 mRNA levels were up-regulated in the 2mg/L DEX-treated zebrafish. The up-regulation may be related to programming effect of DEX in the zebrafish larvae, causing overcompensation mechanism to increase the mRNA levels. Furthermore, DEX treatment caused negative impact on the development and maturation of the testes, in particular spermatogenesis. Therefore, immature gonadal development may cause positive feedback by increasing GnRH and Kiss. This indicates that DEX can alter the regulation of GnRH2, GnRH3, Kiss1 and Kiss2 in adult zebrafish, which affects maturation of gonads. Computer analysis of 1.5 kb region upstream of the 5' UTR of Kiss1, Kiss2, GnRH2 and GnRH3 promoter showed that there are putative binding sites of glucocorticoid response element and transcription factors involved in stress response. GnRH3 promoter analysed from pre-optic area, ventral telencephalon and ventral olfactory bulb showed higher methylation at CpG residues located on -1410, -1377 and -1355 between control and 2mg/L DEX-treated groups. Hence, early-life DEX treatment can alter methylation of GnRH3 gene promoter, which subsequently affects gene regulation and reproductive functions.
    Matched MeSH terms: Zebrafish/metabolism
  13. Sequence and localization of kcnk10a in the brain of adult zebrafish (Danio rerio)
    Loganathan K, Moriya S, Sivalingam M, Ng KW, Parhar IS
    J. Chem. Neuroanat., 2017 Dec;86:92-99.
    PMID: 29074372 DOI: 10.1016/j.jchemneu.2017.10.004
    kcnk10a has been predicted in zebrafish to be a member of the two-pore domain potassium ion (K+) channel-related K+ (TREK) channel family known as a thermoreceptor. Since reproduction is affected by temperature, Kcnk10a could be involved in the regulation of reproduction. However, expression of kcnk10a in the zebrafish brain and association with reproduction has not been identified. In this study, the full length sequence and localization of kcnk10a in the brain was investigated and gene expressions of the TREK channel family were examined to investigate association with reproduction. We initially identified the full length cDNA sequence of kcnk10a using Rapid Amplification of cDNA Ends and localization in the zebrafish brain using in situ hybridization. Furthermore, we examined the gene expression differences of kcnk2b, kcnk10a and kcnk10b mRNA between genders as well as developmental stages by real-time PCR. The deduced amino acid sequence of the identified kcnk10a mRNA contains highly conserved two pore domains and four transmembrane regions and was higher similarity to zebrafish Kcnk10b than zebrafish Kcnk2a and 2b. kcnk10a mRNA was widely distributed in the brain such as the preoptic area, hypothalamus and the midbrain. kcnk10a mRNA expression exhibited significant difference between mature male and female, and increase during puberty. Kcnk10a could be involved in the regulation of reproductive function.
    Matched MeSH terms: Zebrafish/metabolism*
  14. Fulltext Habenular kisspeptin modulates fear in the zebrafish
    Ogawa S, Nathan FM, Parhar IS
    Proc Natl Acad Sci U S A, 2014 Mar 11;111(10):3841-6.
    PMID: 24567386 DOI: 10.1073/pnas.1314184111
    Kisspeptin, a neuropeptide encoded by the KISS1/Kiss1, and its cognate G protein-coupled receptor, GPR54 (kisspeptin receptor, Kiss-R), are critical for the control of reproduction in vertebrates. We have previously identified two kisspeptin genes (kiss1 and kiss2) in the zebrafish, of which kiss1 neurons are located in the habenula, which project to the median raphe. kiss2 neurons are located in the hypothalamic nucleus and send axonal projections to gonadotropin-releasing hormone neurons and regulate reproductive functions. However, the physiological significance of the Kiss1 expressed in the habenula remains unknown. Here we demonstrate the role of habenular Kiss1 in alarm substance (AS)-induced fear response in the zebrafish. We found that AS-evoked fear experience significantly reduces kiss1 and serotonin-related genes (plasmacytoma expressed transcript 1 and solute carrier family 6, member 4) in the zebrafish. Furthermore, Kiss1 administration suppressed the AS-evoked fear response. To further evaluate the role of Kiss1 in fear response, zebrafish Kiss1 peptide was conjugated to saporin (SAP) to selectively inactivate Kiss-R1-expressing neurons. The Kiss1-SAP injection significantly reduced Kiss1 immunoreactivity and c-fos mRNA in the habenula and the raphe compared with control. Furthermore, 3 d after Kiss1-SAP injection, the fish had a significantly reduced AS-evoked fear response. These findings provide an insight into the role of the habenular kisspeptin system in inhibiting fear.
    Matched MeSH terms: Zebrafish/metabolism
  15. Fulltext Biocompatible and Biodegradable Surfactants from Orange Peel for Oil Spill Remediation
    Wang PS, Ahmad A, Nazar M, Rahmah AU, Moniruzzaman M
    Molecules, 2023 Aug 01;28(15).
    PMID: 37570764 DOI: 10.3390/molecules28155794
    Oil spill remediation plays a vital role in mitigating the environmental impacts caused by oil spills. The chemical method is one of the widely recognized approaches in chemical surfactants. However, the most commonly used chemical surfactants are toxic and non-biodegradable. Herein, two biocompatible and biodegradable surfactants were synthesized from orange peel using the ionic liquid 1-butyl-3-methylimidazolium chloride (BMIMCl) and organic solvent dimethylacetamide (CH3CN(CH3)2) as reaction media. The acronyms SOPIL and SOPOS refer to the surfactants prepared with BMIMCl and dimethylacetamide, respectively. The surface tension, dispersant effectiveness, optical microscopy, and emulsion stability test were conducted to examine the comparative performance of the synthesized surfactants. The Baffled flask test (BFT) was carried out to determine the dispersion effectiveness. The toxicity test was performed against zebrafish (Danio rerio), whereas the closed bottle test (CBT) evaluated biodegradability. The results revealed that the critical micelle concentration (CMC) value of SOPIL was lower (8.57 mg/L) than that of SOPOS (9.42 mg/L). The dispersion effectiveness values for SOPIL and SOPOS were 69.78% and 40.30%, respectively. The acute toxicity test demonstrated that SOPIL was 'practically non-toxic' with a median lethal concentration of more than 1000 mg/L after 96 h. The biodegradation rate was recorded as higher than 60% for both surfactants within 28 days, demonstrating their readily biodegradable nature. Considering these attributes, biocompatible and biodegradable surfactants derived from orange peel emerge as a promising and sustainable alternative for oil spill remediation.
    Matched MeSH terms: Zebrafish/metabolism
  16. Nanocomposites of iron oxide, sodium alginate, and eugenol induce apoptosis via PI3K/Akt/mTOR signaling in Hep3 cells and in vivo hepatotoxicity in the zebrafish model
    Elderdery AY, Alzerwi NAN, Alzahrani B, Alsrhani A, Alsultan A, Rayzah M, et al.
    Int J Biol Macromol, 2024 Jan;256(Pt 2):127490.
    PMID: 37979758 DOI: 10.1016/j.ijbiomac.2023.127490
    Hepatic cancer is among the most recurrently detected malignancies worldwide and one of the main contributors to cancer-associated mortality. With few available therapeutic choices, there is an instant necessity to explore suitable options. In this aspect, Nanotechnology has been employed to explore prospective chemotherapeutic approaches, especially for cancer treatment. Nanotechnology is concerned with the biological and physical properties of nanoparticles in the therapeutic use of drugs. In the current work, formulation, and characterization of α-Fe2O3-Sodium Alginate-Eugenol nanocomposites (FSE NCs) using several approaches like SEM and TEM, UV-visible, FTIR, and PL spectroscopy, XRD, EDAX, and DLS studies have been performed. With an average size of 50 nm, the rhombohedral structure of NCs was identified. Further, their anticancer activity against Hep3B liver cancer cell lines has been performed by cell viability, dual staining, DCFH-DA, Annexin-V/-FITC/PI, cell cycle analysis methods, and PI3K/Akt/mTOR signaling proteins were studied to assess the anticancer effects of the NCs in Hep3B cells. Also, anti-cancer activity on animal modeling in-vivo using zebra fishes to hematological parameters, liver enzymes, and histopathology study effectiveness was noticed. Moreover, the NCs reduced the viability, elevated the ROS accumulation, diminished the membrane integrity, reduced the antioxidants, blocked the cell cycle, and triggered the PI3K/Akt/mTOR signaling axis that eventually resulted in cell death. As a result, FSE NCs possess huge potential for use as a possible anticancer candidate.
    Matched MeSH terms: Zebrafish/metabolism
  17. Estrogen directly stimulates LHb expression at the pituitary level during puberty in female zebrafish
    Li G, Tang H, Chen Y, Yin Y, Ogawa S, Liu M, et al.
    Mol Cell Endocrinol, 2018 02 05;461:1-11.
    PMID: 28801227 DOI: 10.1016/j.mce.2017.08.003
    The LHb expression is up-regulated during puberty in female zebrafish. However, the molecular mechanism underlying how LHb expression is regulated during puberty remains largely unknown. In this study, we found that the mRNA expression levels of lhb, fshb and cyp19a1b were up-regulated along with the puberty onset in zebrafish. Among the three nuclear estrogen receptors (nERs), the esr2b is the only type whose expression is significantly up-regulated during puberty onset in the pituitary. However, in situ hybridization results revealed that lhb mRNA was colocalized with esr1 and esr2a but not esr2b. Exposure to estradiol (E2) significantly stimulates LHb expression in both wild-type and kiss1-/-;kiss2-/-;gnrh3-/- triple knockout pubertal zebrafish. Moreover, exposure of cultured pituitary cells to E2 increased the LHb expression, indicating that the estrogenic effect on LHb expression could be acted at the pituitary level. Finally, we cloned and analyzed the promoter of lhb by luciferase assay. Our results indicated that the E2 responsive regions of lhb promoter for ERα and ERβ2 are identical, suggesting that ERα and ERβ2 could bind to the same half ERE region of the promoter of lhb, exhibiting a classical ERE-dependent pathway. In summary, we demonstrate that E2 could directly act on the pituitary level to stimulate LHb transcription during puberty in zebrafish.
    Matched MeSH terms: Zebrafish/metabolism*
  18. Fulltext In Silico and In Vitro Methods in the Characterization of Beta-Carotene as Pharmaceutical Material via Acetylcholine Esterase Inhibitory Actions
    Muthuraman A, Ramesh M, Mustaffa F, Nadeem A, Nishat S, Paramakrishnan N, et al.
    Molecules, 2023 May 26;28(11).
    PMID: 37298835 DOI: 10.3390/molecules28114358
    Molecular docking is widely used in the assessment of the therapeutic potential of pharmaceutical agents. The binding properties of beta-carotene (BC) to acetylcholine esterase (AChE) proteins were characterized using the molecular docking method. The mechanism of AChE inhibition was assessed by an experimental in vitro kinetic study. In addition, the role of BC action was tested by the zebrafish embryo toxicity test (ZFET). The results of the docking ability of BC to AChE showed significant ligand binding mode. The kinetic parameter, i.e., the low AICc value shown as the compound was the competitive type of inhibition of AChE. Further, BC also showed mild toxicity at a higher dose (2200 mg/L) in ZFET assessment with changes in biomarkers. The LC50 value of BC is 1811.94 mg/L. Acetylcholine esterase (AChE) plays a pivotal role in the hydrolysis of acetylcholine, which leads to the development of cognitive dysfunction. BC possesses the regulation of acetylcholine esterase (AChE) and acid phosphatase (AP) activity to prevent neurovascular dysfunction. Therefore, the characterization of BC could be used as a pharmaceutical agent for the treatment of cholinergic neurotoxicity-associated neurovascular disorders such as developmental toxicity, vascular dementia, and Alzheimer's disease due to its AChE and AP inhibitory actions.
    Matched MeSH terms: Zebrafish/metabolism
  19. Fulltext Behavioural, genomics and proteomic approach to examine Alzheimer's disease in zebrafish
    Siddiqui A, Abidin SAZ, Shah ZA, Othman I, Kumari Y
    Comp Biochem Physiol C Toxicol Pharmacol, 2023 Sep;271:109636.
    PMID: 37100105 DOI: 10.1016/j.cbpc.2023.109636
    Globally around 24 million elderly population are dealing with dementia, and this pathological characteristic is commonly seen in people suffering from Alzheimer's disease (AD). Despite having multiple treatment options that can mitigate AD symptoms, there is an imperative call to advance our understanding of the disease pathogenesis to unfold disease-modifying treatments/therapies. To explore the driving mechanisms of AD development, we stretch out further to study time-dependant changes after Okadaic acid (OKA)-induced AD-like conditions in zebrafish. We evaluated the pharmacodynamics of OKA at two-time points, i.e., after 4-days and 10-days exposure to zebrafish. T-Maze was utilized to observe the learning and cognitive behaviour, and inflammatory gene expressions such as 5-Lox, Gfap, Actin, APP, and Mapt were performed in zebrafish brains. To scoop everything out from the brain tissue, protein profiling was performed using LCMS/MS. Both time course OKA-induced AD models have shown significant memory impairment, as evident from T-Maze. Gene expression studies of both groups have reported an overexpression of 5-Lox, GFAP, Actin, APP, and OKA 10D group has shown remarkable upregulation of Mapt in zebrafish brains. In the case of protein expression, the heatmap suggested an important role of some common proteins identified in both groups, which can be explored further to investigate their mechanism in OKA-induced AD pathology. Presently, the preclinical models available to understand AD-like conditions are not completely understood. Hence, utilizing OKA in the zebrafish model can be of great importance in understanding the pathology of AD progression and as a screening tool for drug discovery.
    Matched MeSH terms: Zebrafish/metabolism
  20. Time dependent effect of chronic embryonic exposure to ethanol on zebrafish: Morphology, biochemical and anxiety alterations
    Ramlan NF, Sata NSAM, Hassan SN, Bakar NA, Ahmad S, Zulkifli SZ, et al.
    Behav Brain Res, 2017 08 14;332:40-49.
    PMID: 28559182 DOI: 10.1016/j.bbr.2017.05.048
    Exposure to ethanol during critical period of development can cause severe impairments in the central nervous system (CNS). This study was conducted to assess the neurotoxic effects of chronic embryonic exposure to ethanol in the zebrafish, taking into consideration the time dependent effect. Two types of exposure regimen were applied in this study. Withdrawal exposure group received daily exposure starting from gastrulation until hatching, while continuous exposure group received daily exposure from gastrulation until behavioural assessment at 6dpf (days post fertilization). Chronic embryonic exposure to ethanol decreased spontaneous tail coiling at 24hpf (hour post fertilization), heart rate at 48hpf and increased mortality rate at 72hpf. The number of apoptotic cells in the embryos treated with ethanol was significantly increased as compared to the control. We also measured the morphological abnormalities and the most prominent effects can be observed in the treated embryos exposed to 1.50% and 2.00%. The treated embryos showed shorter body length, larger egg yolk, smaller eye diameter and heart edema as compared to the control. Larvae received 0.75% continuous ethanol exposure exhibited decreased swimming activity and increased anxiety related behavior, while withdrawal ethanol exposure showed increased swimming activity and decreased anxiety related behavior as compared to the respective control. Biochemical analysis exhibited that ethanol exposure for both exposure regimens altered proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. Our results indicated that time dependent effect of ethanol exposure during development could target the biochemical processes thus leading to induction of apoptosis and neurobehavioral deficits in the zebrafish larvae. Thus it raised our concern about the safe limit of alcohol consumption for pregnant mother especially during critical periods of vulnerability for developing nervous system.
    Matched MeSH terms: Zebrafish/metabolism
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